PhotoDiode Amplifier Design with Howland Current Inverter

[@STEMprof]

A PhotoDiode Receiver Amplifier Circuit with Howland Current source/inverter is analyzed in this video.. For more analog circuit videos see: PhotoDiode Amplifier with Data Compression Explained kzbin.info/www/bejne/nqLVg6toqst0rck PhotoDiode Amplifier with Op Amp and MOSFET Explained kzbin.info/www/bejne/Z5SWdn1omZmjjKs Analog Computer Raises signal to the Power signal kzbin.info/www/bejne/h5aWlIxvf7itj8k Amplifier with -25 to 55 dB Attenuation-Gain range kzbin.info/www/bejne/pardZ5-KfMlljtE Electronic Gain Control for Op Amp Amplifier kzbin.info/www/bejne/hKCxmISml89qbbs Thermometer Circuit Design with Op Amp & BJT transistor kzbin.info/www/bejne/a2a8pKWXe6pjqMk Instrumentation Amplifier with Electronic Gain Control kzbin.info/www/bejne/eWXXmJuQYtZpkNU Power Amplifier Design (Class A) with Transformer kzbin.info/www/bejne/nXzPe6WnfNaYeas VCA Electronic Gain Control (Part 1): Voltage-Controlled Attenuator Overview kzbin.info/www/bejne/mXfdio2phaqnhpI Analog Multiplier Circuit kzbin.info/www/bejne/jIGYZHRor9WJg7M Push-Pull Power Amplifier Design with Op Amp, Sziklai Darlington Transistors kzbin.info/www/bejne/bnOpq6afbJKJmNU Analog Vector Summer Circuit Design with Op Amp and BJT Transistors kzbin.info/www/bejne/hnqkpJRmhrOJpNU Op Amp Analog Computer Differential Equation Solver kzbin.info/www/bejne/e3_UZGx7mtiZhtk Push-Pull Power Amplifier with Darlington Transistors kzbin.info/www/bejne/bmeZfoyfl9Rrr6c And the Analog Circuits Video playlist: kzbin.info/aero/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these Circuit design and analysis videos are interesting.

[@ChiefBridgeFuser]

I recall that bias on photodiodes is used to reduce the junction capacitance and thus increase speed/bandwidth. I also recall that the downside of biasing is increased noise. So, in high sensitivity, low speed (like a photometer for chemical measurements) zero bias is desirable.

[@STEMprof]

Thanks for sharing your thoughts and insights.

[@ernestb.2377]

i learn a lot from this. I miss a little bit of reasoning why and when should one use such a circuit. Facts about the advantages and disadvantages.

[@STEMprof]

Glad that this video is helpful. The first Op Amp operates as a transimpedance Amplifier by converting weak current of photodiode to a practical voltage at its output. The 2nd Op Amp uses that voltage to generate a reversed direction current source proportional to the original current value. I hope this is helpful.

[@ernestb.2377]

@STEMprof Yes, I really enjoy following your explanations. But I meant in general, for other videos too. For example, this video: why would one want that reversed current source, as we just could use the first voltage as the voltage output with low output impedance. In other words, it would be beneficial (in my opinion) to explain beforehand a video why should one use specific configuration, typical use cases, why not use maybe another obvious configuration, pitfalls and so on. Don't get me wrong, your circuit analysis is very interesting to follow along 😀

[@STEMprof]

Thabk you for sharing your thoughts & comment. Glad that you like my videos. I understand your point. In some design problems (including this one) the desired output is not a low impedance voltage and instead a high impedance current source (not sink) is required proportional to the input. This is a design for such use case. I hope this is helpful.

[@ernestb.2377]

Great!

[@STEMprof]

Thank you! Glad that you like this photodiode amplifier video. For more sensor videos pls see the Sensors Amplifiers playlist kzbin.info/aero/PLrwXF7N522y7Ut9bm8TXAOhIWqL__FGlj

[@Chupacabras222]

Very interesting, as always :) but I see one problem there. If the first opamp is powered by 5V, and Ipd can go to 1mA, than Rp cannot be 10k pot. Because V2 would not be able to go to 13V.

[@STEMprof]

Glad that you found this video interesting. Thank you for sharing your observations. You have a good point. 👍 Either max 2k Ohm potentiometer should be used or op amp supply has to be say +15v. For more sensor videos pls see the Sensors Amplifiers playlist kzbin.info/aero/PLrwXF7N522y7Ut9bm8TXAOhIWqL__FGlj Thank you